PowerPoint
Powerpoint (oddly enough) is probably the simplest way to draw trees on the computer. One major benefit is that you can draw trees from the bottom up, which is useful if you're still trying to work out their structure.
Sapling
A nice web app for drawing trees is Sapling. Note that you have to build the trees from the top down (i.e. starting with the root node and proceeding downward). This works best if you already know what the tree will look like—so I'd recommend drawing the tree on paper first, then recreating it in Sapling.
TreeForm
To draw trees while offline, if you plan to do a lot of tree-building, or you have more complex trees, TreeForm is a great option. Note that you will need to have Java installed.
Mac users can install TreeForm by double clicking tree-form-install.pkg in the downloaded file; Windows users should unzip TreeFormWindows.zip then double click TreeForm.bat (if that doesn't work you can try double clicking TreeForm.jar).
Bracket notation
Linguists sometimes use bracket notation to represent trees in a compact form. Consider the following example:
[S [NP Bob ] [VP ate ] ]
There are a number of online services that will let you input a tree in bracket notation and will pop out an image for you. Perhaps the most popular is Miles Shang's Syntax Tree Generator, shown here:
Some bracket notation converters include:- Miles Shang's Syntax Tree Generator
- RSyntaxTree
- jsSyntaxTree
- qtree (for LaTeX)
- forest (for Latex)